1. Field of the Invention
The present invention relates to a transmission or transaxle, and, more particularly, to a brake apparatus for braking a transmission or transaxle which automatically compensates for brake pad wear
2. Description of the Related Art
Transmissions and transaxles typically include a brake assembly operable to apply braking force thereto. Typically, braking force is applied to the speed reduction mechanism of the transmission or transaxle. In one typical brake apparatus, a brake pad is axially displaced a predetermined distance to frictionally engage a component (e.g., a brake disc) rotationally fixed to a shaft of the speed reduction mechanism to effect braking of the transmission or transaxle. Additionally, a friction backing pad may be utilized to engage the side of the brake disk opposite the brake pad when the brake is engaged. Repeated engagement of the brake assembly causes the material of the brake pad to wear away and, consequently, the axial displacement which formerly engaged the brake is no longer sufficient to effect braking activity. It is therefore desirable that the brake assembly be adjusted to account for brake pad wear and the consequent decrease in brake pad thickness. Prior brake mechanisms required manual adjustment to account for brake pad wear. Such manual adjustments are time consuming to perform and lead to operational down time.
Mechanisms of the prior art have sought to provide a self adjusting brake system to eliminate manual adjustment and the associated problems. Prior art self adjusting brake systems typically utilize a nut threaded to a shaft together with a ratchet mechanism. Typically, a disc having ratchet teeth is connected to the nut and operably engaged with a pawl affixed to the brake lever, with the nut determining the axial position of the brake lever. The brake lever includes a cam surface whereby actuation of the brake lever actuates the brake pad to effect braking. As the brake apparatus is utilized, and the brake pad wears, the nut is axially displaced along the shaft supporting the brake pad and thereby axially displaces the brake lever. Self adjusting brakes of this type are mounted exterior to the transmission or transaxle upon which they act, and, therefore, require additional space, and can be damaged by debris.
What is needed in the art is a self adjusting brake system which eliminates manual adjustment to compensate for brake pad wear and which does not require additional apparatus exterior to the transmission or transaxle housing.
The present invention provides an improved self adjusting brake for use with a transmission or transaxle, wherein it is desired to provide a self adjusting brake mechanism which does not require additional apparatus exterior to the transmission or transaxle housing and which brake apparatus comprises an internal xe2x80x9cwetxe2x80x9d type brake. The current invention utilizes a brake pad or brake pad assembly having a ramp surface cooperating with the brake pad and an actuator for engaging the ramp surface and thereby actuating the brake pad. The ramp surface of the current invention allows for self adjustment of the brake mechanism. As the brake pad wears and consequently decreases in thickness, the actuator will progressively engage the ramp surface to effect braking activity. In one exemplary embodiment, the actuator includes a ramp surface which mates with the ramp surface cooperating with the brake pad. The self adjusting brake of the current invention is internally positioned in the transmission or transaxle casing and is therefore lubricated by the transmission or transaxle which advantageously mitigates part wear.
The invention, in one form thereof, comprises a transaxle including a hydrostatic transmission module housed in a hydrostatic transmission module casing. The hydrostatic transmission module includes an output shaft. An axle module is housed in an axle module casing and includes a pair of axles, a reduction gear train and a gear train input shaft detachably connectable to the output shaft of the hydrostatic transmission. The axle module casing is separable into a plurality of axle casing components along a split line substantially perpendicular to the axles. A brake assembly for braking the axle module is mounted internally in the axle casing.
The invention, in another form thereof, comprises a transmission including a housing with a speed reduction mechanism operably positioned therein. A brake assembly is supported by the housing and is operable to selectively apply braking force to the speed reduction mechanism. The brake assembly includes a brake pad, a stepped ramp surface, and an actuator for selectively engaging the stepped ramp surface and thereby actuating the brake pad.
The invention, in a further form thereof, comprises a hydrostatic transaxle including a hydrostatic transmission and a housing with a speed reduction mechanism operatively positioned therein and coupled to the hydrostatic transmission. A brake assembly is supported by the housing and is operable to selectively apply braking force to the speed reduction mechanism. In this form of the current invention, the brake assembly comprises a brake pad having a brake pad ramp surface, and an actuator for selectively engaging the brake pad ramp surface and thereby actuating the brake pad.
The invention, in yet another form thereof, comprises a transmission including housing with a speed reduction mechanism operably positioned therein. A brake assembly is supported by the housing and is operable to selectively apply braking force to the speed reduction mechanism. The brake assembly comprises an actuator and a brake pad having mating ramp surfaces so that movement of the actuator in a given direction engages the mating ramp surfaces and transmits movement of the actuator into movement of the brake pad.
The invention, in yet a further form thereof, comprises a transaxle including a variable speed transmission and a housing with a speed reduction mechanism and a differential operably positioned therein. The housing rotatably supports a pair of axles drivingly connected to the differential. A brake assembly is supported by the housing and is operable to selectively apply braking force to the speed reduction mechanism. In this form of the current invention, the brake assembly comprises a brake pad having a brake pad ramp surface and a brake cam for selectively engaging the ramp surface and thereby actuating the brake pad.
In one form of the current invention, a differential lock is provided so that the differential may be locked and equal power transmitted to each of the axles.
An advantage of the present invention is the ability to eliminate manual adjustment of a brake mechanism utilized to apply braking force to a transmission or transaxle.
Another advantage of the present invention is the ability to provide a self adjusting wet brake housed in a transmission or transaxle casing.
A further advantage of the present invention is the ability to provide a self adjusting brake which does not require additional apparatus exterior to a transmission or transaxle housing.
Yet another advantage of the present invention is the provision of a self adjusting brake of relatively simple construction.